“He isn’t a cartoonist, really. He’s a fine artist.”

Ralph Steadman's "The Pessimists" for the centenary issue of the New Statesman

Late on Tuesday I stumbled into the back room at the British Cartoon Museum and helped myself to a glass of wine. I was on the guest list, but the gallery was heaving and nobody was paying much attention to the door. It was the first night of a Ralph Steadman retrospective, organised around the artist’s 77th birthday. Men and women of all ages were gathered in small groups, drinking and ogling the images.

I knew Ralph would be attending the event and I was determined to grab him for an interview. The problem was, I had no idea what he looked like. I had only his Self-Portrait to go on: an elephantine head with an oil well extruding from one eye and an enormous, beaky nose. It’s the first thing you see on entering the exhibition room.

Steadman’s imagination is monstrous. His drawings, paintings and sculptures accentuate everything that is misshapen about human beings. He has a knack for it. The larger works are spectacular, shocking, occasionally sublime. An antiwar tableau screams: “How you gonna crucify a child in Vietnam without any arms?” It looks just as it sounds – a torn anthropoid cutlet straddling a wooden cross. And around the corner hangs “The Peacekeepers are coming!” – in which a wave of shrieking Grenadians flees heavily armed optimists sent in by the UN.

Most know his style before they know his name. Images from his long collaborations with Hunter S Thompson and Will Self (see The Pessimists for the centenary NS, above) have become fast rooted in our visual culture; so have his illustrated editions of Animal Farm and Alice in Wonderland. And when you stand amid wall-to-wall Steadman, the range of his oeuvre becomes apparent: Gothic landscapes, still lives, experimental photography. Sometimes he simply draws cats. I never did find Ralph at the opening, because he wasn’t there. When I spoke to him the following day he told me he had been unwell. “I’m laid up,” he said. “It’s a bloody nuisance.”

We talked about political cartoons. “You know I haven’t drawn David Cameron yet? I just can’t stand the idea of it. I refer to him as Bubble Face.” I mentioned Steve Bell’s “Rubberman”, and he agreed. “A condom, if you prefer – one with a hole in it.”

Back at the exhibition, experts had grimaced when I mentioned his cartoons. “He isn’t a cartoonist, really,” Louisa Buck, a PhD candidate in comics studies told me. “He’s a fine artist.”

“In some ways ‘cartoonist’ is a derogatory term,” Steadman said. “People have said it to me dozens of times – you’re just a cartoonist. But I’m rather keen on the Wittgenstein bit about the only thing of value being what you cannot say.

“That’s the thing about drawing: when you try to say something in pictures, it gains a dimension that language can’t match. I like that.”